{"id":"CVE-2026-49283","aliases":["DEBIAN-CVE-2026-49283","EUVD-2026-62502","GHSA-6929-8p9f-26jx","UBUNTU-CVE-2026-49283"],"status":"published","title":"SimpleSAMLphp HTTP-Artifact TLS validator confusion allows cross-IdP authentication bypass","description":"The SimpleSAMLphp SAML2 library is a PHP library for SAML2 related functionality. Prior to versions 4.19.3, 4.20.2, 5.0.6, and 6.2.1, the HTTPArtifact::receive() flow can treat an unsigned embedded SAML Response as cryptographically valid for the wrong identity provider. SOAPClient::addSSLValidator() attaches a TLS-based validator to the outer SOAP ArtifactResponse, while the embedded Response receives a validator that delegates to the outer message and is later checked against metadata selected from the embedded response issuer rather than necessarily the artifact issuer. SOAPClient::validateSSL() returns normally when the TLS public key does not match the key being validated, and SAML2\\Message::validate() treats a validator call that does not throw as successful. In a multi-IdP federation, a malicious or lower-trust IdP can therefore provide an ArtifactResponse containing an unsigned Response that claims a higher-trust victim IdP as issuer and authenticate as arbitrary users with attacker-chosen assertion attributes, NameID, and session data. This issue is fixed in versions 4.19.3, 4.20.2, 5.0.6, and 6.2.1.","severity":{"version":"3.1","score":8.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-09","score":0.00472,"percentile":0.41082,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-295"],"published":"2026-07-02T20:25:56Z","modified":"2026-11-04T10:47:22Z","fixes":[{"ecosystem":"Packagist","package":"simplesamlphp/saml2","fixed_in":["6.2.1","5.0.6","4.20.2","4.19.3"],"sources":["ghsa","osv"]},{"ecosystem":"Packagist","package":"simplesamlphp/saml2-legacy","fixed_in":["4.20.2","4.19.3"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"Packagist","package":"simplesamlphp/saml2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.0.0"},{"fixed":"6.2.1"}]}]},{"source":"ghsa","ecosystem":"Packagist","package":"simplesamlphp/saml2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.0.0"},{"fixed":"5.0.6"}]}]},{"source":"ghsa","ecosystem":"Packagist","package":"simplesamlphp/saml2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.20.0"},{"fixed":"4.20.2"}]}]},{"source":"ghsa","ecosystem":"Packagist","package":"simplesamlphp/saml2-legacy","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.20.0"},{"fixed":"4.20.2"}]}]},{"source":"ghsa","ecosystem":"Packagist","package":"simplesamlphp/saml2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.19.3"}]}]},{"source":"ghsa","ecosystem":"Packagist","package":"simplesamlphp/saml2-legacy","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.19.3"}]}]},{"source":"osv","ecosystem":"Debian:12","package":"simplesamlphp","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.19.7-1","1.19.7-1+deb12u1","1.19.7-1+deb12u2","1.19.7-2","2.1.8-0.1","2.2.6-1","2.3.11-1","2.3.11-2","2.4.8-1","2.5.3.1-1"]},{"source":"osv","ecosystem":"Debian:14","package":"simplesamlphp","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.10.0-1","1.11.0-1","1.12.0-1","1.12.0~rc1-1","1.12.0~rc2-1","1.13.0-1","1.13.1-1","1.13.1-2","1.13.2-1","1.14.0-1","1.14.1-1","1.14.10-1","1.14.11-1","1.14.15-1","1.14.2-1","1.14.2-2","1.14.3-1","1.14.4-1","1.14.5-1","1.14.6-1","1.14.7-1","1.14.8-1","1.14.9-1","1.15.0-1","1.15.1-1","1.15.2-1","1.15.3-1","1.15.4-1","1.16.0-1","1.16.1-1","1.16.2-1","1.16.3-1","1.17.0-1","1.17.1-1","1.17.2-1","1.17.2-2","1.17.3-1","1.17.4-1","1.17.5-1","1.17.6-1","1.17.6-2","1.18.1-1","1.18.4-1","1.18.5-1","1.18.6-1","1.18.7-1","1.18.8-1","1.19.0-1","1.19.1-1","1.19.1-1.1","1.19.6-1","1.19.7-1","1.19.7-2","1.6.0-1","1.6.1-1","1.6.2-1","1.6.3-1","1.6.3-2","1.6.3-3","1.7.0-1","1.7.0-2","1.8.0-1","1.8.1-1","1.8.2-1","1.9.0-1","1.9.0~rc1-1","1.9.0~rc2-1","1.9.1-1","1.9.2-1","2.1.8-0.1","2.2.6-1","2.3.11-1","2.3.11-2","2.4.8-1","2.5.3.1-1"]},{"source":"osv","ecosystem":"Packagist","package":"simplesamlphp/saml2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.0.0"},{"fixed":"6.2.1"}]}],"versions":["v6.0.0","v6.0.1","v6.1.0","v6.1.1","v6.1.2","v6.1.3","v6.1.4","v6.1.5","v6.1.6","v6.2.0"]},{"source":"osv","ecosystem":"Packagist","package":"simplesamlphp/saml2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.0.0"},{"fixed":"5.0.6"}]}],"versions":["v5.0.0","v5.0.1","v5.0.2","v5.0.3","v5.0.4","v5.0.5"]},{"source":"osv","ecosystem":"Packagist","package":"simplesamlphp/saml2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.20.0"},{"fixed":"4.20.2"}]}],"versions":["v4.20.0","v4.20.1"]},{"source":"osv","ecosystem":"Packagist","package":"simplesamlphp/saml2-legacy","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.20.0"},{"fixed":"4.20.2"}]}],"versions":["v4.20.0","v4.20.1"]},{"source":"osv","ecosystem":"Packagist","package":"simplesamlphp/saml2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.19.3"}]}],"versions":["4.6.9","v0.1.0","v0.1.0-alpha","v0.3.0","v0.4.0","v0.4.1","v0.4.2","v0.5.0","v0.6.0","v0.6.1","v0.6.2","v0.6.3","v0.6.4","v0.7.0","v0.7.1","v0.8.0","v0.8.1","v1.0.0","v1.1.0","v1.10","v1.10.1","v1.10.2","v1.10.3","v1.10.4","v1.10.5","v1.10.6","v1.2.0","v1.3.0","v1.3.1","v1.3.2","v1.4.0","v1.5.0","v1.5.1","v1.5.2","v1.5.3","v1.5.4","v1.6.0","v1.6.1","v1.7.0","v1.7.1","v1.7.2","v1.8","v1.8.1","v1.8.2","v1.9","v1.9.1","v1.9.2","v2.0.0","v2.0.1","v2.1","v2.2","v2.3","v2.3.1","v2.3.2","v2.3.3","v2.3.4","v2.3.5","v2.3.6","v2.3.7","v2.3.8","v2.3.9","v3.0.0","v3.0.1","v3.0.2","v3.0.3","v3.1.0","v3.1.1","v3.1.2","v3.1.3","v3.1.4","v3.1.5","v3.1.6","v3.2","v3.2.1","v3.2.2","v3.2.3","v3.2.4","v3.2.5","v3.2.6","v3.3.0","v3.3.1","v3.3.10","v3.3.11","v3.3.2","v3.3.3","v3.3.4","v3.3.5","v3.3.6","v3.3.7","v3.3.8","v3.3.9","v3.4.0","v3.4.1","v3.4.2","v3.4.3","v3.4.4","v3.4.5","v4.0.0","v4.0.1","v4.0.2","v4.0.3","v4.1.0","v4.1.1","v4.1.10","v4.1.11","v4.1.12","v4.1.2","v4.1.3","v4.1.4","v4.1.5","v4.1.6","v4.1.7","v4.1.8","v4.1.9","v4.16.14","v4.17.0","v4.18.0","v4.18.1","v4.19.0","v4.19.1","v4.19.2","v4.2.0","v4.2.1","v4.2.2","v4.2.3","v4.2.4","v4.2.5","v4.2.6","v4.2.7","v4.2.8","v4.3.0","v4.3.1","v4.4.0","v4.4.1","v4.5.0","v4.5.1","v4.6.0","v4.6.1","v4.6.10","v4.6.11","v4.6.12","v4.6.13","v4.6.14","v4.6.15","v4.6.16","v4.6.2","v4.6.3","v4.6.4","v4.6.5","v4.6.6","v4.6.7","v4.6.8"]},{"source":"osv","ecosystem":"Packagist","package":"simplesamlphp/saml2-legacy","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.19.3"}]}],"versions":["4.6.9","v0.1.0","v0.1.0-alpha","v0.3.0","v0.4.0","v0.4.1","v0.4.2","v0.5.0","v0.6.0","v0.6.1","v0.6.2","v0.6.3","v0.6.4","v0.7.0","v0.7.1","v0.8.0","v0.8.1","v1.0.0","v1.1.0","v1.10","v1.10.1","v1.10.2","v1.10.3","v1.10.4","v1.10.5","v1.10.6","v1.2.0","v1.3.0","v1.3.1","v1.3.2","v1.4.0","v1.5.0","v1.5.1","v1.5.2","v1.5.3","v1.5.4","v1.6.0","v1.6.1","v1.7.0","v1.7.1","v1.7.2","v1.8","v1.8.1","v1.8.2","v1.9","v1.9.1","v1.9.2","v2.0.0","v2.0.1","v2.1","v2.2","v2.3","v2.3.1","v2.3.2","v2.3.3","v2.3.4","v2.3.5","v2.3.6","v2.3.7","v2.3.8","v2.3.9","v3.0.0","v3.0.1","v3.0.2","v3.0.3","v3.1.0","v3.1.1","v3.1.2","v3.1.3","v3.1.4","v3.1.5","v3.1.6","v3.2","v3.2.1","v3.2.2","v3.2.3","v3.2.4","v3.2.5","v3.2.6","v3.3.0","v3.3.1","v3.3.10","v3.3.11","v3.3.2","v3.3.3","v3.3.4","v3.3.5","v3.3.6","v3.3.7","v3.3.8","v3.3.9","v3.4.0","v3.4.1","v3.4.2","v3.4.3","v4.0.0","v4.0.1","v4.0.2","v4.0.3","v4.1.0","v4.1.1","v4.1.10","v4.1.11","v4.1.12","v4.1.2","v4.1.3","v4.1.4","v4.1.5","v4.1.6","v4.1.7","v4.1.8","v4.1.9","v4.16.14","v4.17.0","v4.18.0","v4.18.1","v4.19.0","v4.19.1","v4.19.2","v4.2.0","v4.2.1","v4.2.2","v4.2.3","v4.2.4","v4.2.5","v4.2.6","v4.2.7","v4.2.8","v4.3.0","v4.3.1","v4.4.0","v4.4.1","v4.5.0","v4.5.1","v4.6.0","v4.6.1","v4.6.10","v4.6.11","v4.6.12","v4.6.13","v4.6.14","v4.6.15","v4.6.16","v4.6.2","v4.6.3","v4.6.4","v4.6.5","v4.6.6","v4.6.7","v4.6.8"]},{"source":"osv","ecosystem":"Ubuntu:Pro:16.04:LTS","package":"simplesamlphp","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.13.2-1","1.14.0-1","1.14.0-1ubuntu2","1.14.0-1ubuntu2+esm1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:18.04:LTS","package":"simplesamlphp","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.14.15-1","1.15.0-1","1.15.1-1","1.15.2-1","1.15.3-1","1.15.3-1ubuntu0.1~esm1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:20.04:LTS","package":"simplesamlphp","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.17.5-1","1.17.6-1","1.17.6-2","1.18.1-1","1.18.4-1","1.18.4-1ubuntu0.1~esm1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:22.04:LTS","package":"simplesamlphp","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.19.1-1","1.19.1-1.1","1.19.1-1.1ubuntu0.1~esm1"]},{"source":"osv","ecosystem":"Ubuntu:24.04:LTS","package":"simplesamlphp","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.19.7-1","1.19.7-1+deb12u1ubuntu0.1"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"simplesamlphp","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.19.7-2","2.1.8-0.1","2.2.6-1","2.3.11-1","2.3.11-2","2.4.8-1","2.5.3.1-1"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"simplesamlphp","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.19.7-2"]}],"products":[{"vendor":"simplesamlphp","product":"saml2"}],"references":[{"url":"https://github.com/simplesamlphp/saml2/security/advisories/GHSA-6929-8p9f-26jx","tags":["x_refsource_CONFIRM","advisory","web"]},{"url":"https://github.com/simplesamlphp/saml2/commit/4a71b20d8d845579fd0a54d6449c265b40db459d","tags":["x_refsource_MISC","fix"]},{"url":"https://github.com/simplesamlphp/saml2/commit/a2c1ac588c70d7b7998546cf32675fb113f22a5f","tags":["x_refsource_MISC","fix"]},{"url":"https://github.com/simplesamlphp/saml2/commit/d5c213132ef671c0018a11252322034dbddd735a","tags":["x_refsource_MISC","fix"]},{"url":"https://github.com/simplesamlphp/saml2/commit/e2df7992609964951b2a3e7d6566b7427b2a968f","tags":["x_refsource_MISC","fix"]},{"url":"https://github.com/advisories/GHSA-6929-8p9f-26jx"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/49xxx/CVE-2026-49283.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-49283","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-49283","tags":["advisory"]},{"url":"https://github.com/simplesamlphp/saml2","tags":["package"]},{"url":"https://ubuntu.com/security/CVE-2026-49283","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-49283","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2026-49283","title":"SimpleSAMLphp HTTP-Artifact TLS validator confusion allows cross-IdP authentication bypass","description":"The SimpleSAMLphp SAML2 library is a PHP library for SAML2 related functionality. Prior to versions 4.19.3, 4.20.2, 5.0.6, and 6.2.1, the HTTPArtifact::receive() flow can treat an unsigned embedded SAML Response as cryptographically valid for the wrong identity provider. SOAPClient::addSSLValidator() attaches a TLS-based validator to the outer SOAP ArtifactResponse, while the embedded Response receives a validator that delegates to the outer message and is later checked against metadata selected from the embedded response issuer rather than necessarily the artifact issuer. SOAPClient::validateSSL() returns normally when the TLS public key does not match the key being validated, and SAML2\\Message::validate() treats a validator call that does not throw as successful. In a multi-IdP federation, a malicious or lower-trust IdP can therefore provide an ArtifactResponse containing an unsigned Response that claims a higher-trust victim IdP as issuer and authenticate as arbitrary users with attacker-chosen assertion attributes, NameID, and session data. This issue is fixed in versions 4.19.3, 4.20.2, 5.0.6, and 6.2.1.","status":"published","published":"2026-08-19T14:47:05.519Z","modified":"2026-08-19T18:19:10.978Z","cvss":[{"version":"3.1","score":8.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N","level":"high","assessor":"cna"}],"cwes":["CWE-295"],"updated_at":"2026-11-02T13:35:10.963527Z"}],"euvd":[{"id":"EUVD-2026-62502","description":"The SimpleSAMLphp SAML2 library is a PHP library for SAML2 related functionality. Prior to versions 4.19.3, 4.20.2, 5.0.6, and 6.2.1, the HTTPArtifact::receive() flow can treat an unsigned embedded SAML Response as cryptographically valid for the wrong identity provider. SOAPClient::addSSLValidator() attaches a TLS-based validator to the outer SOAP ArtifactResponse, while the embedded Response receives a validator that delegates to the outer message and is later checked against metadata selected from the embedded response issuer rather than necessarily the artifact issuer. SOAPClient::validateSSL() returns normally when the TLS public key does not match the key being validated, and SAML2\\Message::validate() treats a validator call that does not throw as successful. In a multi-IdP federation, a malicious or lower-trust IdP can therefore provide an ArtifactResponse containing an unsigned Response that claims a higher-trust victim IdP as issuer and authenticate as arbitrary users with attacker-chosen assertion attributes, NameID, and session data. This issue is fixed in versions 4.19.3, 4.20.2, 5.0.6, and 6.2.1.","status":"published","published":"2026-08-19T14:47:05Z","modified":"2026-08-19T18:19:10Z","cvss":[{"version":"3.1","score":8.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N","level":"high"}],"updated_at":"2026-11-02T18:01:40.9092Z"}],"ghsa":[{"id":"GHSA-6929-8p9f-26jx","title":"SimpleSAMLphp HTTP-Artifact TLS validator confusion allows cross-IdP authentication bypass","description":"## Summary\n\nSimpleSAMLphp's HTTP-Artifact receive path can treat an unsigned embedded SAML `Response` as cryptographically valid for the wrong IdP.\n\nIn the `HTTPArtifact::receive()` flow, the SOAP `ArtifactResponse` receives a TLS-based validator from `SOAPClient::addSSLValidator()`. The embedded SAML `Response` then receives a validator that delegates signature validation to that outer `ArtifactResponse`. Later, the SP validates the embedded `Response` against metadata selected from the embedded response issuer, not necessarily the artifact issuer.\n\nThe critical issue is that `SOAPClient::validateSSL()` returns normally when the TLS public key does not match the key currently being validated. `SAML2\\Message::validate()` treats any validator call that does not throw an exception as successful. As a result, an `ArtifactResponse` obtained from one IdP can validate an unsigned embedded SAML `Response` that claims to be issued by a different IdP.\n\nIn a multi-IdP/federation deployment where a malicious or lower-trust IdP can issue an HTTP-Artifact response to an SP, this can allow the attacker to authenticate to the SP as arbitrary users from a higher-trust victim IdP.\n\n## Impact\n\nA malicious or lower-trust IdP in the same SP/federation trust set can authenticate to the SP as users from another IdP when HTTP-Artifact is used. The attacker can choose assertion attributes, `NameID`, and session data in the forged unsigned assertion.\n\nThis is an authentication bypass and identity-provider impersonation issue. In realistic federations, the security boundary between IdPs matters: a compromised or low-assurance IdP should not be able to mint identities for a high-assurance IdP.","status":"published","published":"2026-07-02T20:25:56Z","modified":"2026-08-04T21:25:27Z","cvss":[{"version":"3.1","score":8.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N","level":"high"}],"cwes":["CWE-295"],"updated_at":"2026-11-02T14:40:56.852119Z"}],"nvd":[{"id":"CVE-2026-49283","description":"The SimpleSAMLphp SAML2 library is a PHP library for SAML2 related functionality. Prior to versions 4.19.3, 4.20.2, 5.0.6, and 6.2.1, the HTTPArtifact::receive() flow can treat an unsigned embedded SAML Response as cryptographically valid for the wrong identity provider. SOAPClient::addSSLValidator() attaches a TLS-based validator to the outer SOAP ArtifactResponse, while the embedded Response receives a validator that delegates to the outer message and is later checked against metadata selected from the embedded response issuer rather than necessarily the artifact issuer. SOAPClient::validateSSL() returns normally when the TLS public key does not match the key being validated, and SAML2\\Message::validate() treats a validator call that does not throw as successful. In a multi-IdP federation, a malicious or lower-trust IdP can therefore provide an ArtifactResponse containing an unsigned Response that claims a higher-trust victim IdP as issuer and authenticate as arbitrary users with attacker-chosen assertion attributes, NameID, and session data. This issue is fixed in versions 4.19.3, 4.20.2, 5.0.6, and 6.2.1.","status":"published","published":"2026-08-19T15:17:07.027Z","modified":"2026-09-18T20:09:01.757Z","cvss":[{"version":"3.1","score":8.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N","level":"high","assessor":"secondary"}],"cwes":["CWE-295"],"updated_at":"2026-11-02T14:12:39.962615Z"}],"osv":[{"id":"CVE-2026-49283","title":"SimpleSAMLphp HTTP-Artifact TLS validator confusion allows cross-IdP authentication bypass","description":"The SimpleSAMLphp SAML2 library is a PHP library for SAML2 related functionality. Prior to versions 4.19.3, 4.20.2, 5.0.6, and 6.2.1, the HTTPArtifact::receive() flow can treat an unsigned embedded SAML Response as cryptographically valid for the wrong identity provider. SOAPClient::addSSLValidator() attaches a TLS-based validator to the outer SOAP ArtifactResponse, while the embedded Response receives a validator that delegates to the outer message and is later checked against metadata selected from the embedded response issuer rather than necessarily the artifact issuer. SOAPClient::validateSSL() returns normally when the TLS public key does not match the key being validated, and SAML2\\Message::validate() treats a validator call that does not throw as successful. In a multi-IdP federation, a malicious or lower-trust IdP can therefore provide an ArtifactResponse containing an unsigned Response that claims a higher-trust victim IdP as issuer and authenticate as arbitrary users with attacker-chosen assertion attributes, NameID, and session data. This issue is fixed in versions 4.19.3, 4.20.2, 5.0.6, and 6.2.1.","status":"published","published":"2026-08-19T14:47:05.519Z","modified":"2026-11-04T10:47:22.843437967Z","cvss":[{"version":"3.1","score":8.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N","level":"high"}],"cwes":["CWE-295"],"updated_at":"2026-11-04T11:07:06.271559Z"},{"id":"DEBIAN-CVE-2026-49283","description":"The SimpleSAMLphp SAML2 library is a PHP library for SAML2 related functionality. Prior to versions 4.19.3, 4.20.2, 5.0.6, and 6.2.1, the HTTPArtifact::receive() flow can treat an unsigned embedded SAML Response as cryptographically valid for the wrong identity provider. SOAPClient::addSSLValidator() attaches a TLS-based validator to the outer SOAP ArtifactResponse, while the embedded Response receives a validator that delegates to the outer message and is later checked against metadata selected from the embedded response issuer rather than necessarily the artifact issuer. SOAPClient::validateSSL() returns normally when the TLS public key does not match the key being validated, and SAML2\\Message::validate() treats a validator call that does not throw as successful. In a multi-IdP federation, a malicious or lower-trust IdP can therefore provide an ArtifactResponse containing an unsigned Response that claims a higher-trust victim IdP as issuer and authenticate as arbitrary users with attacker-chosen assertion attributes, NameID, and session data. This issue is fixed in versions 4.19.3, 4.20.2, 5.0.6, and 6.2.1.","status":"published","published":"2026-08-19T15:17:07.027Z","modified":"2026-10-01T03:03:24.662393892Z","cvss":[{"version":"3.1","score":8.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N","level":"high"}],"updated_at":"2026-11-02T15:45:56.444225Z"},{"id":"GHSA-6929-8p9f-26jx","title":"SimpleSAMLphp HTTP-Artifact TLS validator confusion allows cross-IdP authentication bypass","description":"## Summary\n\nSimpleSAMLphp's HTTP-Artifact receive path can treat an unsigned embedded SAML `Response` as cryptographically valid for the wrong IdP.\n\nIn the `HTTPArtifact::receive()` flow, the SOAP `ArtifactResponse` receives a TLS-based validator from `SOAPClient::addSSLValidator()`. The embedded SAML `Response` then receives a validator that delegates signature validation to that outer `ArtifactResponse`. Later, the SP validates the embedded `Response` against metadata selected from the embedded response issuer, not necessarily the artifact issuer.\n\nThe critical issue is that `SOAPClient::validateSSL()` returns normally when the TLS public key does not match the key currently being validated. `SAML2\\Message::validate()` treats any validator call that does not throw an exception as successful. As a result, an `ArtifactResponse` obtained from one IdP can validate an unsigned embedded SAML `Response` that claims to be issued by a different IdP.\n\nIn a multi-IdP/federation deployment where a malicious or lower-trust IdP can issue an HTTP-Artifact response to an SP, this can allow the attacker to authenticate to the SP as arbitrary users from a higher-trust victim IdP.\n\n## Impact\n\nA malicious or lower-trust IdP in the same SP/federation trust set can authenticate to the SP as users from another IdP when HTTP-Artifact is used. The attacker can choose assertion attributes, `NameID`, and session data in the forged unsigned assertion.\n\nThis is an authentication bypass and identity-provider impersonation issue. In realistic federations, the security boundary between IdPs matters: a compromised or low-assurance IdP should not be able to mint identities for a high-assurance IdP.","status":"published","published":"2026-07-02T20:25:56Z","modified":"2026-08-04T21:30:19.900068063Z","cvss":[{"version":"3.1","score":8.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N","level":"high"}],"cwes":["CWE-295"],"updated_at":"2026-11-02T15:46:39.618611Z"},{"id":"UBUNTU-CVE-2026-49283","description":"The SimpleSAMLphp SAML2 library is a PHP library for SAML2 related functionality. Prior to versions 4.19.3, 4.20.2, 5.0.6, and 6.2.1, the HTTPArtifact::receive() flow can treat an unsigned embedded SAML Response as cryptographically valid for the wrong identity provider. SOAPClient::addSSLValidator() attaches a TLS-based validator to the outer SOAP ArtifactResponse, while the embedded Response receives a validator that delegates to the outer message and is later checked against metadata selected from the embedded response issuer rather than necessarily the artifact issuer. SOAPClient::validateSSL() returns normally when the TLS public key does not match the key being validated, and SAML2\\Message::validate() treats a validator call that does not throw as successful. In a multi-IdP federation, a malicious or lower-trust IdP can therefore provide an ArtifactResponse containing an unsigned Response that claims a higher-trust victim IdP as issuer and authenticate as arbitrary users with attacker-chosen assertion attributes, NameID, and session data. This issue is fixed in versions 4.19.3, 4.20.2, 5.0.6, and 6.2.1.","status":"published","published":"2026-08-19T15:17:00Z","modified":"2026-10-17T12:58:32.116889616Z","cvss":[{"version":"3.1","score":8.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N","level":"high"}],"updated_at":"2026-11-02T16:56:33.391918Z"}]}}